1. Field of the Invention
This invention relates to process and apparatus for drying seed cotton and like materials so that the cotton passing through the apparatus contains moisture within a predetermined range of moisture content. More particularly, this invention relates to process and apparatus for drying seed cotton in a cotton gin plant.
2. Description of the Prior Art
In processing seed cotton in a gin plant, it has been practice to dry the cotton to an optimum moisture content before ginning so that the ginning is most efficiently performed. In addition, it is conventional to clean the cotton of foreign matter before stripping the fiber from the seeds. Proper drying is important to preserve staple length. On the other hand, insufficient drying makes more difficult subsequent operations such as cleaning and sometimes causes reduction in the value of the ginned cotton. Ordinarily, the cotton may have a moisture content of from 8% (percent) to 18% or more, whereas the optimum moisture content is in the range of 3%-10%; for example, about 5%.
As noted in prior U.S. Patents such as U.S. Pat. No. 3,114,613, there has been a prior practice of experienced operators inspecting the cotton in its delivered condition and estimating the amount of heat that had to be supplied for drying. This estimation, corrected with periodic inspections, required an extremely capable operator and then was not scientific and less than perfect. As described in U.S. Pat. Nos. 3,114,613, and 3,280,474, an improvement was made where the moisture content was measured scientifically through measuring resistance of the incoming cotton and this signal then employed, alone or with an additional signal coming from the moisture sensing means in the effluent cotton, to control the amount of heat added to dry the cotton to the optimum moisture content in the effluent cotton.
Other patents such as U.S. Pat. Nos. 3,277,581, and 3,364,587, used different approaches for drying materials such as yarn or cotton. Earlier patents such as U.S. Pat. Nos. 2,968,874 and 3,370,360, had apparatus for analyzing either moisture content or the temperature control for drying. Of these patents the most pertinent ones appeared to be U.S. Pat. Nos. 3,114,613, and 3,280,474 employing resistance measuring as indicative of the moisture content of the cotton. These patents have the disadvantage, however, that a single moist leaf or the like in the incoming cotton is reflected by an erroneously high moisture content that caused excessive heat to be imparted to the system. This upsets the control system and causes excessive drying or excessive hunting on the controls.